Ball joints are frequently used in the prior art in motor vehicles, where the joints are exposed to high loads. Axial and radial joints are known in this connection. As is known, the designation of radial or axial joint refers to the main direction of stress of the ball joint in question. Thus, axial joints are primarily subjected to tensile and/or compressive loads parallel to the longitudinal axis thereof. Radial joints, on the other hand, are primarily subjected to loads transverse to the longitudinal axis thereof.
In the case of high temperatures within the ball joint, which, in the case of axial joints, for example, are caused by a direct coupling to a steering system that is hot from operation, the ball socket expands, which results in an unwanted increase in the torque within the ball joint. In order to overcome the disadvantages of thermal expansion, known ball sockets are provided with specially arranged slots. Furthermore, the ball socket may have different material thicknesses.
Continuously slotted ball sockets that are known from the prior art, for example such as a snap-fit socket, are unsuitable due to the increased tendency of such sockets to creep, as well as to have a reduced support surface, since, due to the slots, the ball socket does not rest against the housing with the entire surface thereof, and thus it is possible for the material to creep into the open space between the slots. The material thickness or, respectively, the thickness of the ball socket decreases, however, as a result of the creeping, which leads to play in the ball joint.
In particular in the case of an axial joint, the slots in the region of the opening in the housing are disadvantageous, since high loads occur, caused by tensile forces in the direction of the opening in the housing. In addition, due to the necessary deflection angle of the stud, the opening of the joint housing must be relatively large. As a result, only a small contact area is available between the ball, the ball socket and the joint housing for transferring the tensile forces. Decisive for the contact area is the area in which the ball and inner wall of the housing overlap.
In order to compensate for wear and to minimize the play within the ball joint, it is known from the prior art that ball joints may be designed having a separate elastic adjustment element such as a rubber ring, for example. DE69407894 T2 discloses an axial joint, in which an adjustment element is formed in a lower, elastic region of the ball socket, which is facing away from the ball stud or, respectively, the opening in the housing.